EP1673788A2

EP1673788A2 - Magnetic core winding method, apparatus, and product produced therefrom

Info

Publication number: EP1673788A2
Application number: EP04795101A
Authority: EP
Inventors: Matthew Sweeney; John Medema; Michael Roeber
Original assignee: Actown Electrocoil Inc
Current assignee: Actown Electrocoil Inc
Priority date: 2003-10-15
Filing date: 2004-10-14
Publication date: 2006-06-28
Also published as: WO2005039255A2; TWI295808B; TW200516613A; KR20060057013A; JP2007508718A; US7154368B2; CA2537245A1; WO2005039255A3; CN1868010A; US7124977B2; CN1868010B; IL174550A0; JP4519138B2; US20050082932A1; EP1673788A4; US20050218257A1; US7159816B2; KR100808448B1; HK1099408A1; US20050247815A1

Abstract

The invention relates to winding wire (150) around a magnetic core (200). The invention includes forming corners (158) on the wire that align with inside corners of the magnetic core (200) such that the wire (150) is more tightly wound around the magnetic core (200). The invention also includes pinching a portion of wire (150) that is positioned on the internal diameter of a magnetic core (200) when the wire (150) is wound around the core (200) to provide more turns of the wire (150) around the magnetic core (200) . A magnetic inductor made in accordance with the present invention can have increased inductance, lower temperature rise, smaller size, and exhibit less EMI noise than the prior art.

Description

MAGNETIC CORE WINDING METHOD, APPARATUS, AND PRODUCT PRODUCED THEREFROM

Field of the Invention

[ 1 ] The present invention relates to winding wire on a magnetic core and to apparatuses used

to wind the wire around the magnetic Gore, and related to transformers and inductors produced

from the same.

Background of the Invention

[2] . Prior United States Patents of magnetic core winders, which include but are not limited to

toroidal winders, include U.S. Patents 5,331,729; 4,379,527; 4,872,618; 6,557,793; 4,288,041;

and 5,875,988. In general, the prior art, as shown in FIGS. 1 through 3, illustrate the principle of

winding magnet wire on a magnetic core (hereinafter "core") to create an inductor. The prior art

uses a supply ring 10 arid winding ring 20 with pullout or open/close type ring openings 12 and

22 to enable a core 30 to be arranged with the rings 10 and 20 passing through the center hole of

the core 30. In the prior art the openings 12 and 22 are opened manually and the core 30 is

passed through the openings so that each ring passes through the center hole 32 of the core, with

the central axis 34 of the magnetic core 30 at right-angles to the central axis 25 of the rings.

[3] The supply ring 10 has a U-shaped groove 14 around its circumference. In order to

enable wire 40 to be wound into the groove 14, the end of the wire 40 is manually attached to the

supply ring 10. The winding ring 20 has substantially the same diameter as the supply ring 10,

with which it is aligned concentrically. The winding ring 20 has a wire guide 24 via which wire

40 is drawn from the supply ring 10 and a guide roller 26 to guide the wire 40. [4] In an actual winding operation, the core 30 is first manually inserted onto the rings 10

and 20 via the openings 12 and 22 and positioned as shown in FIG. 2. The end of the wire 40 is

then attached to the supply ring 10 and the supply ring 10 is rotated around its central axis to

wind the required amount of wire 40 into the groove 14. After cutting the trailing end of the wire

40, the cut end is passed through the wire guide 24 and around the guide roller 26, and is drawn

radially outwards from between the rings and affixed to a retainer means or the like (not shown)

provided on the periphery of the core 30.

[5] As shown by FIG. 3, when the core 30 is being wound, a drive (not shown) is used to

rotate the supply ring 10 and winding ring 20 in the opposite direction from that used to load the

wire 40 onto the supply ring 10, and the wire 40 is drawn from the supply ring 10 through the

wire guide 24 and guide roller 26 on the winding ring 20 and attached to the core 30. In this

state, the wire wound around the supply ring 10 is spirally wound a required number of turns

around the core 30, and the wire left over on the supply ring 10 is manually removed. Finally,

the core wound with the wire, that is, the inductor, is removed.

[6] The ideal single layer inductor would have a low temperature rise, high inductance, and

small size. Moreover, it has been found that by increasing the wire size, total number of turns,

and decreasing the core size, these more desirable properties can be achieved. Moreover, since

rectangular wire has a smaller width then round wire (for a given gauge), rectangular wire may

be used to increase the number of turns on a core and thus increase the inductance. As such, US

Patents directed to manufacturing or forming rectangular wire from round wire are found in the

art, for example, US Patent 6,553,650.

[7] The winding of rectangular wire on the edge however is extremely difficult. Referring

now to FIG 4, when the wire 40 forms around the corners 34 of the core 30, the wire has a tendency to twist and lie diagonally. If the wire 40 is guided tightly on either side of the corner,

the twisting can be prevented but in winding a core there is insufficient space to guide the wire as

it wraps around the internal wall 36 of the core 30. In some instances, the rectangular wire is

foπned and the core has a piece cut therefrom which permits the wire to be slipped onto the core.

However, when a piece is removed the magnetic properties may decrease and the inductance of

the core may be reduced.

[8] It is thus an object of the present invention to overcome the problems associated with the

prior art while maintaining an inductor with a low temperature rise, high inductance, and a small size.

Summary of the Invention

[9] In view of the above drawbacks of the prior art, an object of the present invention is to

provide an inductor with lower temperature rise, higher inductance, smaller size, or less EMI noise when compared to an inductor made in accordance with the prior art.

[10] To achieve the above object, the present invention provides a core to be wound with a

wire. A portion of the wire is first wrapped around an outer edge of a form tool positioned in

front of the core. The outer edge of the form tool is shaped similarly to the inside diameter of the

core. Once the portion of the wire is formed around the form tool, the portion of the wire will be preformed with a shape that matches the inside shape of the core. Thus, providing a tight fit

around such the inside diameter of the core. The form tool can be retracted such that the wire

can be pulled through the core wherein the preformed portion of the wire aligns with the inside

shape of the core. This process can be repeated until the core is wound to form an inductor. This

process is also preferred when the wire is rectangular. In an embodiment where the wire is round, the wire once formed around the form tool is flattened or pinched. The pinched portion of

the wire once wound around the core will allow a more efficient winding around the core and

thereby provide an inductor with a lower temperature rise, higher inductance, or smaller size.

The process can be achieved with either an automatic winding apparatus or using a manually hook winding method.

[1 1] After a first layer of wire is wound around the magnetic core, multiple layers can be

wound using the same process to form transformers. When switching to a second layer, the form

tool should be replaced with a second form tool that has an outside shape that matches the inside

shape of the first layer of wire, such that the second layer of wire winds closely around the first

layer.

[12] The process of providing an inductor with a formed wire as described above may be

manufactured with rectangular wire or round wire and by manual hook winding process or on an automatic winder.

Brief Description of the Drawings

[13] A fuller understanding of the foregoing may be had by reference to the accompanying

drawings, wherein:

[14] FIG 1 is a disassembled perspective view of a prior art shuttle;

[ 15] FIG 2 is a perspective view of a prior art shuttle;

[16] FIG 3 shows the direction of rotation of the shuttle and the run of the wire during

winding using a prior art winder;

[ 17] FIG 4 illustrates the supplying of the wire during each rotation of the shuttle of a prior art

winder; [ 18] FIG 5 shows the main parts of a core automatic winding apparatus in accordance with the present invention;

[19] FIG 6 is the core automatic winding apparatus of FIG 5 rotated 180°;

[20] FIG 7 shows the core automatic winding apparatus of FIG 5 with the flattening tool

pinching the wire;

[21] FIG 8 is the core automatic winding apparatus of FIG 6 with the forming tool retracted;

[22] FIG 9a is a cross sectional view of the core and forming tool illustrating the wire wrapped

around the forming tool;

[23] FIG 9b is a cross sectional view of the core of FIG 9a with the forming tool retracted;

[24] FIG 10 is a cross sectional view of the core with the wire pinched and with the forming tool retracted;

[25] FIG 11 a is a side view of an inductor;

[26] FIG 11 b is a cross sectional view of the inductor of FIG 11a;

[27] FIG lie is a side view of a transformer that includes two different gauge wires, each

wound around approximately half of a magnetic core;

[28] FIG 12 shows the main parts of a hook winding apparatus in accordance with one

embodiment of the present invention;

[29] FIG 13 is a perspective view of the hook winding apparatus from FIG 12 illustrating the

flattening tool pinching the wire;

[30] FIG 14 is a perspective view of the hook winding apparatus from FIG 12 illustrating the

flattening tool and the form tool being retracted;

[31] FIG 5 is a perspective view of the hook winding apparatus from FIG 12 illustrating the

wire being pulled tight around the core; [32] FIG 16a is a perspective view of a hook winding apparatus with a guide tool positioned

about the form tool to prevent a rectangular wire from warping while the wire is spirally wound

around a core; and

[33] FIG 16b is a perspective view of the hook winding apparatus with the guide tool partially

removed from the form tool table, done for illustration purposed only.

Detailed Description of the Embodiments

[34] While the invention is susceptible to embodiments in many different forms, there are

shown in the drawings and will be described herein, in detail, the preferred embodiments of the

present invention. It should be understood, however, that the present disclosure is to be

considered an exemplification of the principles of the invention and is not intended to limit the

spirit or scope of the invention and/or claims of the embodiments illustrated. [35] Referring now to FIG 5 there is illustrated a magnetic core automatic winding apparatus

100 (winder) according to the present invention. In this embodiment, the winder 100 includes a

supply ring and a winding ring, referred to herein as a shuttle 102. A shuttle rotation mechanism

(not shown) drives the shuttle 102, while a core rotation mechanism and support 106 rotates a

magnetic core 200. The apparatus 100 further includes a control unit 105 for controlling the

rotation mechanisms 112 and 106.

[36] The magnetic core 200 (referred to herein as "core") is generally, but not limited to

electrical oval or other noncircular core shapes and may be as shown toroidal in shape-

Moreover, the magnetic core 200 may or may not have a solid ring, such^' that the ring may

include liquid or hybrid liquid/solid interior. [37] The shuttle 102 includes a U-shaped winding groove (not shown) for holding a wire 150

and a shuttle guide roller 108 that guides the wire 150 out of the shuttle 102. The shuttle rotation

mechanism is used to independently rotate the shuttle such that the wire 150 can be pulled out of

the shuttle 102. The shuttle rotation mechanism includes a drive roller 112 that engages and

drives the shuttle 1 2. In addition, a plurality of drive support rollers 114 may be included to

help guide or rotate the shuttle during the winding of the core 200.

[38] The apparatus 100 may also include a brake mechanism 104, also controlled by the control unit 105, for placing tension on the wire 150. The brake mechanism 104 includes a first

brake piece 104a and a second brake piece 104b secured about the shuttle 102. The second brake

piece 104b is suspended from the first brake piece 104a by pins 110. When the brake

mechanism is activated by the control unit 105, tension is applied to the wire 150, such that the

wire 150 is maintained in a taut position.

[39] The core rotation mechanism 106 includes two drive rollers 116 located at a specified

point along the shuttle 102, with one drive roller above the shuttle 102 and the other below. The

two drive rollers 1 16 engage the core 200 such that when operating the core 200 may rotate

about its axis.

[40] Referring also to FIGS 6 through 8, the automatic winder 100 further includes a form table 130 positioned and aligned with the core 200. The form table 130 includes a form tool 132

that is horizontally moveable in relation to the form table 130. The form tool 132 may thus be

moved a specified distance D (FIG 9a) from the outside wall 206 of the core 200. The specified

distance is defined as being substantially equal to the length of the outside wall 206 of the core

200. The form tool 132 is also retractable within the form table 130, which as explained in

greater detail below, is done^' when the wire 150 is wrapped around the core 200. [41] Referring also to FIG 9a, the form tool 132 includes an outside profile 135 that is

substantially the same as an inside profile 205 defined by the core 200. As used throughout this

invention the outside profile 135 of the form tool 132 maybe defined as just the outside wall 136

or may be defined to include the sidewalls 138. Furthermore the inside profile 205 defined by

the core 200 may include just the inside wall 207 or may be defined to include the sidewalls 209

such that any corners formed between the inside wall 207 and the sidewalls 209 are defined by

the definition of the inside profile of the core 200. Thus, the inside profile of the core 200 may

include straight, rounded, or slightly arced corners. Irregardless of the exact shape, it is an

important aspect of the invention that the form tool have a matching profile such that the wire

150 is wound tight against the inside profile 205 of the core 200. Moreover, as used in this

invention, the core may include an outside profile 206 that may include any portion not covered

by the inside profile 205.

[42] If the wire 150 is rectangular, the wire 150 is wrapped around the form tool 132 and then

the form tool 132 is retracted (shown in FIG 9b as being removed for clarity, and as seen in FIG

8 the form tool 132 is recessed down into the form table 130). The wire 150 thus includes a

preformed portion 154 (identified between numerals 152) that substantially aligns with the inside

profile 205 defined by the core 200. As such, the core 200 will be wrapped with a more tightly

fitted wire providing for an ideal inductor.

[43] Continuing to refer to FIG 7, if the wire 150 is round, the automatic winder 100 is also

equipped with a flattening tool 160. The flattening tool used, may be, pneumatic presses,

hydraulic presses, toggle presses, flywheel type presses, or hammers. The flattening tool 160

includes a notched section 162 that accommodates for the form tool 132. When the flattening

tool 1 0 is pressed down onto the wire 150 (FIG 7) the preformed portion 154 of the wire 150 is pinched or substantially flattened. Once flattened the flattening tool 160 is lifted away from the

forming table 130 and the forming tool 132 is retracted (FIG 8) to permit the preformed and

flattened wire 150 to be pulled and wrapped around the core 200.

[44] Illustrated in FIG 10, the preformed portion 154 of the wire 150 is flattened and is shown

as having a larger thickness than the non-flattened portion, illustrated generally as flattened

preformed wire 156. It is appreciated by those skilled in the art that the portion of the flattened

wire 150 may be less or more than what is illustrated without departing from the teachings

herein. Moreover, the substantial change in thickness of the wire 150 is done only to illustrate

that a change in thickness has taken place. The change in thickness may be less dramatic such as

that formed by a tapering region between the flattened and non-flattened portions of the wire

150.

[45] The core 200 is then rotated and the process is repeated until the desired turns are made

spirally wrapping to form a inductor 210, illustrated in FIGS Ha and l ib. By flattening or

pinching the portion of wire, the width is reduced which allows more turns per layer of the wire

around the core. This creates an inductor 210. that can have a lower temperature rise, higher

inductance, and be smaller in size as compared to an inductor made in accordance to the prior

art. As illustrated, the wire 150 is pinched preferably at an angle such that there is a tapering

region 158 from the unpinched wire to the pinched wire.

[46] It is appreciated from the present invention that after the core is spirally wound,

additional layers of wire may be added. The teachings of the invention provide that a form tool

have an outside, profile that matches the inside profile of the layer of wire that the additional

layer is placed thereon. In. addition, different gauge wires may be used on the same core, as

illustrated in FIG 1 lC. A first gauge wire 150a is spirally wound around a first portion 220a of a core 200 and a second gauge wire 150b is spirally wound around a second portion 220b of the same core 200.

[47] The angle at which the wire is pinched may be different to achieve various results.

However, the angle which permits the most amount of turns for a given wire will depend upon

the inside of the core when the outside turns are touching each other. Mathematically, the angle

is determined by the following

[48] angle = sin^"

[49] When the present invention is employed the following characteristics were determined:

(1) increase inductance - using the present invention, more turns of the same wire size can be

added to the same core, this will increase the inductance of the inductor when all other things

remain equal; (2) lower temperature rise - the present invention allows a larger diameter wire to fit into the internal diameter of the core without changing the size of the core, a larger diameter wire reduces the copper losses and will therefore reduce the temperature rise; (3) decrease size -

the present invention allows more turns of the same wire size to be wound around a smaller core

and therefore decreases the size and weight, as such a smaller design will be able to have the

same inductance and temperature rise; and (4) decrease noise - the present invention also decreases the electro magnetic interference ("EMI") or noise normally produced by an inductor;

this is due to the gap between the start and finish of the wound wire, as the larger gap decreases

EMI.

[50] The core 200 may also be wound manually in a process known as "hook winding." The

present invention includes winding a core by a hook winding process and apparatus with the additional feature of forming corners in the wire that correspond to the inside corners of the core

and/or flattens or pinches a portion of the wire that wraps around the side wall, inside corners

and inside wall of the core. It also being appreciated that the pinched portion may be more or

less then what is illustrated herein.

[51] Referring now to FIGS 12 through 15, a hook winding apparatus 300 is illustrated and a

method for winding a core using said apparatus will be disclosed. A wire 150 (typically round

for this example) is provided with a lead portion 151 secured to a post 302. The post 302 may be

provided on the core rotation mechanism and support 106. The wire 150 is wrapped around the

form tool 132 and placed in a hook 312 that is extended to an initial position from a hook support

310. The hook 312 is retracted to pull the wire around the form tool 132 to form a preformed

portion 154 (such as shown in FIG 9b) in the wire 150. The wire is then pinched prior to

winding around the core. A flattening or pinching tool 160 is pressed down onto the wire 150

(FIG 13). As mentioned above the wire may be pinched about the preformed portion 154 that

corresponds to the inside profile of the core 200. The wire may include a tapering region

between the pinched portion and unpinched portion. The.. flattening tool 160 and the form tool

132 is retracted (FIG 14). The wire 150 is pulled tight around the core 200 (FIG 15) such that

the pinched preformed portion aligns with the inside profile of the core 200. The core 200 is

rotated, the form tool 132 is extended, and the hook 312 is extended or placed in the initial

position. The process is repeated until the core is spirally wound with the wire 150 with the

formed corners.

[52] Referring now to FIG 16a and FIG 16b in another embodiment, a hook winding

apparatus 400 is used with a rectangular wire 402 with a lead portion 404 secured to a post 306.

The post 306 may be provided on a core rotation mechanism and support 408. The wire 402 is wrapped around a form tool 410 with an outside profile as previously discussed. The wire 402 is

also placed in a hook 412 that is extended to an initial position from a hook support 414. The

hook 412 is retracted to pull the wire around the form tool 410 to form a preformed portion 416

in the wire 402. A guide tool 420 is used to guide the rectangular wire around the form tool 410

without having the wire twist or wrap around when the preformed portion is being formed. The

form tool 410 is retracted (not shown) and the wire 402 is pulled tight around the core 425 such that the preformed portion 416 aligns with the inside profile of the core 425. The core 425 is

rotated and form tool 410 is extended. The hook 412 is also extended or placed in the initial

position. The process is repeated until the core is spirally wound with the wire 402. While FIG

16b illustrated the guide tool 420 being moved or retracted, it is only moved for purposes of

illustrating other components of the apparatus 400. The guide tool 420 may be fixed in

positioned such that the wire 402 slides between the guide tool 420 and the form table 430.

[53] Comparison between an inductor made in accordance with the present invention being

both formed and pinched (hereinafter "Pinched Wire") to a round-wire inductor is shown in the

following tables:

[54] Table No. 1 represents the "Pinched Wire" calculations for a core such as a Magnetics

Inc. part number 77083-A7 core. Using the present invention an inductance of 245mH and a

temperature rise of 38.5°C was calculated. All calculations in the table are based on a single

layer winding and a minimum start to finish wire spacing of 0.319". This spacing and single

layer winding are necessary to maintain acceptable EMI levels.

[55] Table No. 1 Pinched Wire

Core Size 0.95" ID x 1.57" OD x 0.57" High

Finished Coil Size . 0.77" ID x 1.75" OD x 0.75" High

Wire Size 14 Vi AWG (Pinched dimension 0.038" x 0.090")

Turns 55 Inductance 245 mH

DC Resistance 25 mΩ

Temperature Rise with 12ADC 38.5°C

Spacing between Start & Finish 0.319"

[56] Table No. 2 shows the maximum round wire that can be wound on the same core

(Magnetics Inc. p/n 77083-A7) such that the number of turns are equal to that which was

achieved in the Pinched Wire example above. The calculations show that for an equivalent

inductance the wire size must be reduced to 17 Vi AWG. The reduction in wire size yields a

104% increase in DC Resistance and an 80% increase in temperature rise (as temperature rise °C

= [Total power dissipation mW / Available surface area cm²]^0'833

[57] Table No. 2 Maximum Round Wire Utilizing Same Core

Core Size 0.95" ID x 1.57" OD x 0.57" High

Finished Coil Size 0.86" ID x 1.66" OD x 0.66" High

Wire Size 17 56 AWG

Turns 55

Inductance 245 mH

DC Resistance 51 mΩ

Temperature Rise with 12ADC 69.4°C

Spacing between Start & Finish 0.376"

[58] Table No. 3 shows an 1 1.4% increase in OD necessary to maintain the same Height,

Inductance, and temperature rise as the "Pinched Wire" technique,

[59] Smallest Core/Coil Size for Equivalent Inductance, Temperature Rise, and

Terminal Spacing Using Round Wire

[60] Table No.3

Core Size 0.95 ID x 1.85" OD x 0.57" High

Finished Coil Size 0.84 ID x 1.95" OD x 0.68" High

Wire Size 16 AWG

Turns 46

Inductance 245 mH

DC Resistance 36 mΩ Temperature Rise with 12ADC 42.4°C Spacing between Start & Finish 0.368"

[61 ] From the foregoing and as mentioned above, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the novel

concept of the invention. It is to be understood that no limitation with respect to the specific

embodiments illustrated herein is intended or should be inferred. It is, of course, intended to

cover by the appended claims all such modifications as fall within the scope of the claims.

Claims

1. A method of winding a magnetic core, comprising: providing a shuttle loaded with a wire; arranging a magnetic core on the shuttle with the shuttle passing through a central hole of the magnetic core, the magnetic core having an inside profile; providing a form tool that has an outside profile that substantially corresponds to the

inside profile defined by the magnetic core; and unloading the wire from the shuttle to spirally wind the magnetic core in which the wire

wraps around the outside profile defined by the form tool prior to winding around the magnetic

core for forming a preformed portion defined on said wire that substantially corresponds to the

inside profile defined by the magnetic core.

2. The method of claim 1 further comprising automatically rotating the shuttle for automatically unloading the wire during winding of the magnetic core.

3. The method of claim 2 further comprising rotating the magnetic core about its central

axis such that the magnetic core is spirally wound with the wire during the winding thereof.

4^'. The method of claim 1 further comprising retracting the form tool subsequent to the

preformed portion on said wire.

5. The method of claim 1 further comprising pinching a portion of wire wrapped around the

forming tool.

6. The method of claim 5 further comprising wrapping the wire around the magnetic core

such that the pinched portion of wire wraps around the inside profile defined by the magnetic core.

7. A method of winding a magnetic core comprising: providing a shuttle loaded with a wire; arranging a magnetic core such that the shuttle passing through a central hole of the

magnetic core, the magnetic core having an inside profile; securing a lead of the wire around the magnetic core; providing a form tool that has an outside profile that corresponds to the inside profile defined by the magnetic core; and rotating the shuttle and unloading the wire to wrap the wire around the form tool such

that the wire has a preformed portion that corresponds to the inside profile defined by the

magnetic core; temporarily suspending the rotation of the shuttle; and retracting the form tool and resume rotating the shuttle to draw the wire around the

magnetic core whereby the preformed portion of the wire is aligned with the inside profile

defined by the magnetic core.

8. The method of claim 7 further comprising rotating the magnetic core about its central

axis such that the magnetic core is spirally wound with the wire.

9. The method of claim 7 further comprising flattening a portion of the wire wrapped

around the forming tool prior to retracting the form tool to create a pinched portion of wire.

10. The method of claim 7 further comprising flattening the wire wrapped around the

forming tool prior to retracting the form tool to create a pinched portion of wire that corresponds

to the inside profile defined by the magnetic core.

1 1. The method of claim 10 wherein the step of flattening the wire further includes flattening

the wire at an angle to define a pinched region that tapers from a non-pinched portion of wire to

a pinched portion of wire.

12. A wound magnetic core comprising: a magnetic core having an inside profile and an outside profile; and a wire spirally wound around a portion of the magnetic core, the wire having a pinched

portion and an unpinched portion, the pinched portion abuts the inside profile of the magnetic

core and the unpinched portion abuts the outside profile.

13. The wound magnetic core of claim 12 wherein the wire has a preformed shape that aligns

with inside profile of the magnetic core.

14. A winding apparatus for winding a magnetic core that has an inside profile and an outside

profile, comprising: a shuttle loaded with a wire a magnetic core support that supports a magnetic core so that the shuttle passes through a

central hole of the magnetic core; a form tool that has an outside profile that correspond to the inside profile defined by the

magnetic core; and shuttle rotating means to unload and wrap the wire around the outside profile of the form

tool such that the wire has a preformed portion that corresponds to the inside profile defined by

the magnetic core.

15. The apparatus according to Claim 14 further comprising a means to retract the form tool.

16. The apparatus according to Claim 15 further comprising a pinching tool positioned above

the form tool that when lowered towards said form tool, pinches a portion of wire wrapped

around said outside profile defined by the form tool.

17; The apparatus according to Claim 16, wherein the magnetic. core support includes a

rotation means that rotates a pair of magnetic core rollers, the magnetic core being held by a

prescribed force between the magnetic core rollers, in which state the magnetic core is rotated by

said magnetic core rollers about its central axis.

18. The apparatus according to Claim 15, wherein the pinching tool pinches the portion of

wire at an angle to create a tapering region between the pinched portion of wire and an

unpinched portion of wire.

19. A method of winding a magnetic core, comprising: providing a wire; arranging a magnetic core on a support such that the wire passes through a central hole of the magnetic core, the magnetic core having an inside profile; providing a form tool that has an outside profile that corresponds to the inside profile defined by the magnetic core; wrapping the wire around the outside profile defined by the form tool to create a

preformed portion that corresponds to the inside profile defined by the magnetic core; and winding the wire around the magnetic core, wherein the preformed portion aligns with the inside profile defined by the magnetic core.

20. The method according to Claim 19 further comprising: fastening the wire on a hook after wrapping the wire around the form tool; and retracting the hook to form the preformed portion on the wire.

21. The method according to Claim 19, wherein subsequent to the step of retracting the hook

to form the corners and the portion therebetween on the wire, the method includes the step of

pinching a portion of the wire the corresponds to the inside profile defined by the magnetic core.

22. The method according to Claim 21, wherein the step of pinching a portion of the wire

includes pinching the portion of the wire at an angle to form a tapered region between the

pinched portion and unpinched portion of wire.

23. The method according to Claim 19, wherein the step of providing a wire includes loading

said wire on a shuttle and passing said shuttle through the central hole of the magnetic core and

includes mechanically rotating the shuttle such that the wire is unloaded from the shuttle automatically.

24. The method of claim 19 further comprising a guide tool positioned above the form tool to

guide the wire around the form tool without having the wire warp.

25. A wound magnetic core comprising: a magnetic core having an inside profile; and a wire spirally wound around the magnetic core, the wire having a pinched portion and an unpinched portion, the pinched portion abuts at least the inside profile, and wherein the wire has

a performed portion that aligns with the inside profile of the magnetic core.

26. The wound magnetic core of claim 25, wherein the pinched portion also abuts the iiiside

profile of the magnetic core.

27. The wound magnetic core of claim 26, wherein the unpinched portion abuts at least an

outside profile defined by the magnetic core.

28. An inductor comprising: a magnetic core having an inside profile and an outside profile; and a wire spirally wound around the magnetic core, the wire has preformed portions that

align with the inside profile of the magnetic core.

29. The inductor of claim 28, wherein the wire is rectangular.

30. The inductor of claim 28, wherein the wire is round.

31. The inductor of claim 30, wherein the wire includes alternating pinched and unpinched

portions, wherein the pinched portions abut the inside profile of the magnetic core and the

unpinched portions abut the outside profile of the magnetic core.

32. The inductor of claim 31 , wherein the magnetic core is an toroid.